The present invention relates to apparatus for sizing a yarn sheet, more particularly relates to method and apparatus for sizing a yarn sheet such as warp sheet in an automatically controlled manner without direct immersion of same into a size bath.
In most of the conventional sizing systems, it is quite customary to force the running sheet to be immersed in and travel through a size bath in order to coat the yarn sheet fully with the size. This full immersion of the yarns in the size bath inevitably causes excessive adsorption of watery component of the bath by the yarns composing the sheet. This excessive adsorption of water in the sizing process, which is especially outstanding especially when low concentrated size is used, is very inadvantageous in the later staged drying process of the yarn sheet. Increased adsorption of water in the sizing process naturally connects to lowered efficiency in the drying process, the low drying efficiency forming a fatal bar to high speed running of the machine, i.e. escalation of the total process efficiency. In order to overcome this difficulty, it may be employable either to raise the effective temperature in the drying chamber and/or to elongate the travelling distance of the yarn sheet through the drying chamber.
However, in accordance with the kind of the yarn composing the sheet, there may be some definite limit to the temperature of the yarn during the drying process. One must be very careful in control of the yarn temperature during the drying process especially when any synthetic material or materials are used for the yarns composing the sheet. Thus, in some situations, it is quite difficult or almost impossible to adopt the first measure in order to overcome the above-mentioned difficulty.
The second measure inevitably requires enlargement of the equipment construction and/or the floor space for the equipment. This causes undesirable increase in the plant and equipment investment.
It is the primary object of the present invention to provide apparatus for sizing a yarn sheet which is quite free of the ill influence on the drying process to be caused by excessive water adsorption in the sizing process.
The direct immersion of the yarn sheet in the size bath brings about a further drawback. When the yarn sheet runs through the size bath especially at a high speed, the size bath is stirred by the running yarn sheet itself in addition to the stirring by the rotation of the immersion roller and such stirring develops numerous bubbles in and on the size bath. As is well known, bubbles so developed tend to give ill influence upon the quality of the yarn sheet processed. This also sets a limit to the running speed of the yarn sheet and, accordingly, to the total efficiency in the yarn processing.
It is another object of the present invention to provide method and apparatus for sizing a yarn sheet which is free of ill influence by develop must of bubbles in and on the size bath.
In order to carry out sizing process smoothly, it is preferable that the yarn sheet starts to run through the equipment after all the related work element has been registered at their operative positions and the elements are kept at their registered operative position even during the running of the yarn sheet by inertia after the drive for the yarn sheet is turned off. In addition, it is preferable that the yarn sheet is kept free of contact with the size and free of pressure nip for squeezing purpose. Otherwise, unevenness in the sizing effect on the yarn sheet along the length shall be caused and, an is well known, such uneven sizing effect often cause troubles in the subsequent processes such as the weaving process.
It is the other object of the present invention to provide apparatus for sizing a yarn sheet in a well organized fully automatic fashion in which operations of the work elements taking part in the sizing are controlled in regular sequence.